#include<iostream>
using namespace std;
int a[1010]={1}, b[1010]={1}, c[1010];
int m, n;
int len = 1;
void fun()
{
	int jw = 0;
	for (int i = 0; i < len; i++) {
		c[i] = a[i] + b[i] + jw;
		jw = c[i] / 10;
		c[i] %= 10;
	}
	if (jw) {
		c[len++] = jw;
	}
	for (int i = 0; i < len; i++) {
		a[i] = b[i];
		b[i] = c[i];
	}
}
int main()
{
	cin >> m >> n;
	for (int i = 3; i <= n - m + 1; i++) {
		fun();
	}
	for (int i = len - 1; i >= 0; i--) {
		cout << c[i];
	}
	return 0;
}